The invention relates to an apparatus for recording and/or playing back signals on a magnetic tape carried on two rotatable spools in a cassette. The invention relates particularly to a recording and/or playback apparatus of the kind (hereinafter referred to as "a helical scan recorder") comprising a deck plate, at least one drive spindle for driving one of the spools in the cassette to wind the tape onto that spool and unwind it from the other spool, means for supporting the cassette on the deck plate in a position such that the spool to be driven is coaxial with the drive spindle, a rotary magnetic recording and/or playback head supported for rotation relative to the deck plate, a guide drum for the tape, which drum is supported on the deck plate with its axis coinciding with the axis of rotation of the rotary magnetic head, and tape guide means for pulling part of the tape between the spools out of the cassette and laying it in the cylindrical surface of the guide drum and for subsequently guiding the tape along a helical path around part of said surface of the drum so that the rotary magnetic head can record and/or playback signals on the tape which are arranged in tracks extending obliquely relative to the longitudinal direction of the tape.
The term "guide drum" is to be understood herein to include a drum composed of separate coaxial parts.
In a known helical scan recorder which is described in U.S. Pat. No. 3,660,614, a guide slot is formed in a base plate to define a guide path for a tape guide element which pulls part of the tape out of the cassette and lays it on the surface of the guide drum. It has been found to be of particular importance that the tape guide arrangement ensures that the magnetic tape is guided along a path such that, when the tape is pulled out of the cassette and is laid on the surface of the guide drum, the tape guide element exerts no irregular forces on the tape. Such an arrangement prevents deformation of the tape, which is apt to occur in particular at the edges. Therefore, jerky movements of the tape guide element should also be avoided. These requirements cannot be met, or can be met only inadequately, by means of a guide slot formed in a base plate.